Building construction



May 21, 1963 G. BARONI 3,090,162

BUILDING CONSTRUCTIUN y Y* Y Filed Feb. 25, 1953 4 Sheets-Sheet 1 G/ORG/O BARON/ g 95 BY Y 5cl/)Trad ATTO RNEYS G. BARONI BUILDING CONSTRUCTION 4 Sheets-Sheet 2 Filed Feb. 25, 1953 7 M mw M a #s mf n TA .MN e N5 R .M w .m mm WT 6 A af. m M e M 4 Gm. e, y@ n M z 9 M J.

a d a L W M. w G. l F w m May 21, 1963 G. BARoNl BUILDING CONSTRUCTION 4 Sheets-Sheet 3 Filed Feb. 25, 1953 ATTORNEYS May 21, 1963 G. BARON: 3,090,162

BUILDING CONSTRUCTION Filed Feb. 25., 1953 4 Sheets-Sheet 4` FIG. 20A.

United States Patent O 3,990,162 BUILDING CNSTRUC'IIUN Giorgio Baroni, Baroni Construction torp., 515 Madison Ave., New York, NX. Filed Feb. 25, 1953, Ser. No. 338,749 I7 Claims. (Ci. Sti-52) This invention is in the held of building construction using membrane-type sections having a hyperbolic paraboloidical surface conguration, with straight, substantially rigid edges.

Features of the present invention relate to light-weight prefabricated membrane-type building sections having a hyperbolic paraboloidical form and adapted to be assembled in various ways to form a -wide variety of different types of buildings and to be used for assembling various parts of buildings. These sections are reversible in use and are shaped so as to be stacked together or nested; and thus they may be stored or transported conveniently. They are adapted for rapid, easy assembly with a relatively small amount of labor.

Other `features of the present invention relate to various structural arrangements and elements for use in conjunction with prefrabricated hyperbolic paraboloidical membrane-type sections to provide a great exibility in building construction.

In building construction embodying the present invention, the stresses produced by the weight of the building members and other load factors, such as snow on the roof, and in some structures, such as furniture or machinery within the building, all lie substantially along the direction of the various surfaces of the membranes used in the building. Since the stresses are substantially tangential to the surface, the bending stresses which usually occur in the structural members of buildings are substantially reduced or non-existent. Consequently, in building construction embodying my invention, the relative thickness and weight of many portions of the building such as the roof sections, walls, and foundations can be reduced, and moreover, in many of these buildings the need for the walls to act as supports for the roof is removed, thus eliminating the need for a peripheral foundation at the base of the building.

It is among the advantages of the present invention that it provides prefabricated roof sections having doublesloped inclined hyperbolic paraboloidical surfaces, formed according to an isostatic principle, with straight edge stiiening ribs adapting the sections for assembly with other sections in several different ways to form various roof units, which may be interconnected in various Ways to form a wide variety of many different types of roofs. The sections are reversible and nest with each other so as to occupy a minimum space during transportation and storage prior to construction.

'I'hese roof units are substantially self-supporting over wide spans, whereby their incorporation in larger roofs enables the use of dilerent combinations of skylights and windows, and they require a relatively few supporting columns so that heavy roof-supporting walls and extensive foundation structures are eliminated.

The various objects, aspects, and advantages of the present invention will be in part apparent from and in part pointed out in the following description considered in conjunction with the accompanying drcwings, in which:

FIGURE l is a perspective view of a house having hyperbolic-paraboloidical roof sections;

FIGURE 2 is a perspective vie-w of a hyperbolic-paraboloidical pavilion roof unit 2t) of the type having four supporting columns and being equally hipped on all sides;

FIGURE 3 is a perspective view of a hyperbolic-para- 3,0%,lh2 Patented May ZI, 1963 2 boloidical roof unit `ft2 of the umbrella-type having a single central supporting column;

FIGURE 4 is a perspective view of a hyperbolic-paraboloidical roof unit 22 of the umbrella-type provided with four supporting columns;

FIGURE 5 is a perspective View of a hyperbolic-paraboloidical roof unit 23 of the inverted umbrella-type having a single central supporting column .which also acts as a drain pipe;

FIGURE 6 is a perspective view of a large area roof composed of several umbrella-type of roof units 22a;

FIGURE 7 is a vertical cross sectional view diagonally through the roof shown in FIGURE 6, taken along the line 7 7;

FIGURE 8 is a perspective view of a reversible hyperbolic-paraboloidical section or quadrangle 24 which may be used to assemble the types of roofs mentioned above and other structures;

FIGURE 9 is a perspective view of a roof unit built up fro-m hyperbolic-paraboloidical sections or quadrangles such as section 24 and with skylights incorporated therein;

FIGURE l0 is a perspective view of a large building with a roof built up from some of the roof units discussed above and incorporating skylights therein;

FIGURE Il is a vertical cross sectional Iview taken through the building shown in FIGURE 10, taken along the line yII--11;

FIGURE 12 is a vertical sectional view through the center of a prefabricated housing unit with a centrally supported hyperbolic paraboloidical roof unit and a prefabricated foundation unit;

lFIGURE 13 i-s an enlarged perspective view of a prefabricated `foundation unit;

FIGURE 14 is a vertical sectional view through the center of a housing unit supported from a single foundation block and incorporating hyperbolic paraboloidical sections, such as the sections 2.4, to form the roof surface and floor supporting cantilevers;

FIGURE l5 is a vertical section through the center of a housing unit similar to that shown in FIGURE 14 and incorporating floor arches built from hyperbolic paraboloidical sections;

FIGURE 16 is an enlarged partial perspective view of the peak portion of the roof unit shown in FIGURE 3, with certain parts omitted or broken 'away to show more clearly the construction;

FIGURE 16A is a perspective view of Ian angle brace used in the peak construction shown in FIGURE 16;

FIGURE 17 is a cross sectional view of the column supporting the roof peak `shown in FIGURE 16, taken lalong the line 17-17;

FIGURE 17A -is a cross section showing an alternative column form;

FIGURES 18A and 18B are enlarged sectional views of the ribs along the edges of la prefabricated section, taken along the line-s 13A-48A and ISB- 18B of FIG- URE 16;

FIGURE 18C is a correspondingly enlarged sectional view through the rib along the edge of a prefabnicated section, euch fas the portion of Ia roof shown in FIGURE 20, taken along the line ISC-18C, `and omitting certain structural `details for purposes of illustrati-on;

FIGURES 18D 4and 18E tare corresponding sectional views :of modied edge ribs for roofs;

FIGURE 19 is an enlarged partial perspective view of a corner of the roof unit shown in FIGURE 2;

FIGURE 20 is an enlarged partial perspective view of the center portion of the edge ofthe root `shown in FIG- URE 3;

FIGURE 20A is la partial perspective view of the braces used in the portion of the roof `shown in FIGURE 3;

FIGURE 2l isa partial perspective View of a corner of the roof shown inFIGURE 3,1with certain parts broken away to show more clearly the construction;

FIGURE 22 is 'a perspective view of another type of hyperbolic paraholoidical roof `of the umbrella-type;

FIGURE 23 is an enlarged cross section showing details of construction;

FIGURE 24 is .a perspective view of la non-rectangular roof;

FIGURE 25 is a top view of the roof of FIGURE 24,

FIGURE 26 shows the way dn which prefabricated sections according to my invention will nest With each other for storage and shipping.

Referring -to the drawings in greater detail, FIGURE 8 shows a prefabricated hyperbolic paraholoidical quadrangle section 24 which can be assembled with other sirnilar quadrangle sections to form various rooting suba-ssern'blies and structural elements in which the bending stresses are substantially non-existent. Thus, the Whole central area of the section 24 is made from relatively thin sheet material. Moreover, the section 24 may be built with various forms of straight edge stiiening ribs, as explained 'more in ydetail hereinafter, to facilitate its use in various structures.

For example, in FIGURE l is shown a house having a roof constructed from eight prefabiicated quadrangle sections 31, 32, 33, 34, 35, 36, 37, Yand 33, each similar to the section 24. The four central sections S33, 34, 3S, and 36, are formed into a roof unit 29a, similar to the pavilion roof unit 20 shown in FIGURE 2, which is supported by four columns il (only three are seen), one column under each of the corners thereof. Similarly', the roof unit 20a in the center lof the house may be supported on four columns 42 (-two are shown dotted) which, for example, can be lally columns or reinforced pillars huilt into the walls.

The roof for the house shown in FIGURE 1 includes two ends which are cantilevcred from the central roof unit 20a. Each of these cantilevercd ends includes two pairs of roof sections 31, '32, and 37, 38, respectively. Thus, the whole noo-f is supported from four points, and the walls of the house serve primarily as weather barriers rather than 4as roof supports. Thus, there is no need for a heavy foundation around the base of the perimeter of the house, Inasmuch as the walls do not need to carry any rooting load, they may include extensive windows or side light arcas 44 of pellucid `building materials, which in conventional houses must be sparingly used :or surrounded by heavy structural frames to carry the roof loads. From this description it will be seen that the house :of FIGURE 1 can be enlarged to haven generally cross-shaped floor area by hanging two more pairs of prefahricated hyperbolic paraboloidical sections from 'the other two opposite eaves of the central roof unit 26a. Gther ino-diiications also can be made such as using the sections 3l and 32 to form ya icantilevered roof for 4an open porch, with no pillars to interrupt a persons view from it.

In order to explain more fully the coniiguration of the prefabricated hyperbolic paraboloidical sections used in the roof of the house shown in FIGURE l, reference is again made to the enlarged perspective view of the section 24, shown in FIGURE 8. The section has two horizontal edges, indicated at 45 and 45A, respectively, and two inclined edges indicated at 46 and 46A, respectively, which make yan angle c with the horizontal, as sho-wn. rI'he hoof surface 47 extends between these edges in a continuous, double-curved sheet having a hyperbolic paraboloidical form.

In order to show the curvature of the surface 47, the edge 45 and the edge 46 are each divided into eight equal parts, respectively, and the respective division points are joined by seven equally spaced straight line elements 4S, lying in the surface 47 of the quadrangle section 24. Similarly, the edge 45A ,and fthe edge 416A are each divided into eight equal parts, respectively, and seven other straight line elements 56 all lying in the surface 47, and each intersecting the lines 48 are drawn between the respective division points on edges 45A vand 46A.

In a mathematical sense, these ele-ments 48 and Si) may be called some of the genenating elements for the surface 47, yfor the surface is generated by an innitude of such elements stretching between opposite edges as sli-own, and although these generating elements 48 and 50 are straight, the surface 47 is a double curved surface of the second order. Traces created by the intersection of the surface 47 with planes extending in a diagonal direction from corner to corner of lthe lsection 24 and perpendicular to the plane of the edges 45 and 45A torni la series or family of parab olic curves, for example: such as the dotted curves 5I, 52, and S3, respectively.

The curve Si extends lfrom .the upper corner or peak 55 to the corner 56 and is concave upward. This parabolic curve 51 approaches 'the horizontal direction, i.e. its vertex, near the corner S6, whereas the parabola 52, extending between the other corners 57 and S8 is convex upward and has its vertex S9 at the intersection of the two curves, approximately -i-n the center of the section 24. The panabola 53 is Iformed by the intersection with the surface 47 of a plane which is perpendicular to the plane of the edges 45 and 45A and intersects the inclined edges do land 445A at points which are one quarter of Ithe way ltoward the peak 55 (i.e. by a plane parallel to the plane of the curve 52) `and it is convex upward Awith its vertex on the curve 51. Whole families of such panabolas exist in the surface 47.

The intersections of horizontal planes (ie. being parallel Iwith the edges 45 and 45A) with the surface 47 trace a series or Ifamily of hyperbolic curves. For example, a horizontal rplane through points which are onequ-arter of the way up along each of the inclined edges 46 and 46A, intersects the surface 'along the hyperbolic curve 6h, and a horizontal plane through the mid-points oi these edges lo and 46A forms another hyperbolic curve 6I.

As shown in FIGURE 8, the prefabricated section 24 is bounded by la quadrangle and is shown as having a square perpendicular projection 62 on any horizontal plane. That is, by projecting the four corners 5S, 5.6, 57, `and 58 of the section 24 onto a horizontal plane by means of imaginary projection lines 63, a square pattern 62 results. rIhus, it is seen that although the section 24 has a hyperbolic paraboloidical form, it is bounded by a quadrangle and Imay have a square horizontal projection and thus easily nts together with other sections to form roof units, such as the units 2l), 22, 22', and 23, and other more complex larger area roofs such as the roof of the house shown in FIGURE l, and many other small and large roofs, as explained hereinafter.

There are many types of construction wherein it is more desirable for esthetic reasons or other considerations, to use sections having a rectangular horizontal projection. For example, in the construction 4of homes, rectangular floor patterns are more customary than square door patterns. This may be obtained by relatively increasing either of the opposed pairs of edges, for example, by increasing edges 4S and d5. Thus, it should be understood that these sections can have either rectangular or square projections, and as used `herein the word rectangle is intended to include a square By changing die angle between the edges 45 and 45A, which is lthe same as changing the angle iB in the projection 62, the quadrangle section 24 may be made to have other than rectangular projections, eig. such yas a parallelogram or a rhorn-bus. In general it is preferable to build Prefabricated sections 24 having a rect-angular projection, 4beca-use they are adapted to the widest range :of various uses. However, these other shapes of prea-bnicated sections having more `generalized parabolic and hyperbolic curvatures (ie. non-orthogonal axes) may be built. For example, FIGURES 24 and 25 show a genenally hexagonal roof built from three prefabrioated hyperbolic-paraboloidical sections having a rhombic projection with B equal 120.

An advantage of the hyperbolic-paraboloidical surface of the section 24 is that the stresses therein lie along the direction of the sur-face so that lwhen it is used in a roof or in other structunal arrangements the surface itself assumes the -various loads imposed upon the section. Thus, bending iiexural stresses lare minimized, `and when the section is used in a roof, it is not necessary to use any rafters or equivalent support members which are required to support conventional roofs today. In order to give a rough, even if not mathematically exact, picture of how the stresses align themselves 'in the section 24 shown `in FIGURE 8, consider the four roof sections 24a (FIGURE 3) which are generally simil-ar to 'the section 24 and me connected together to form the roof unit 22 of la rectangular lform with a single center support. Imagine that the unit 22 is uniformly loaded, as by a thick blanket of snow. The surface 47 acts like a stretched membrane `or skin. The outside corner 66, corresponding in position to the corner 56 in section 24 tends to move downwardly and thus a ytension stress occurs in the whole roof section along the direction of the curve 5l so that the corner 56 is in effect Isupported from the peak corner 55 somewhat in the manner as the center of a suspension bridge is supported from either tower by ya cable having a parabolic curve fom.

At the same time, the action of the whole central area of the roof surface around the point S9 is to tend to sag, creating a compression stress 'along the direction of the diagonal parabolic curve 52, much as the load on any parabolic -rarohway causes a compression stress in the arch. The hyperbolic-paraboloidicial surfce 24 represents a materiali/nation of the three-dimensional diagram of the stresses in a uniformly loaded rectangular lroof unit 2.2. For uniformly distributed loads, such stresses all Ilie along the direction of the surface, and they appear as shear (tangential) stresses, consequently resolving themselves into pure ftensions and pure compressions and are substantially uniform all over the surface.

The effect of these stresses in the roof surface is to create a compressive stress in the edges 45 and 45A which is zero at the corner 56 and becomes greatest at the corners 57 and 58. Thus, in Ia roof unit 22 (FIGURE 3) the corners 67 and 68 (corresponding in position to the corners 57 and 53 of the section 24) bear against the adjacent corners of the respective adjacent roof sections of the roof with considerable compressive force, i.e. in the roof 22 there is a compressive stress along the horizontal outside edges which is greatest in the central portions 7i) and decreases toward all four of the outer corners, such as corner 6e. The inclined edge portions 45 and 46A (FIGURE 7) carry tension stresses caused by the distribution of the stresses as explained above, so that there is tension along the inclined ridges or spines 71 (see FIGURE 3) which is least near the regions 7l) and increases ytoward the peak of the roof.

An advantage of the prefabricated section 24 is that it may be used upside down to form roof units of the type shown in FIGURES 2 and 5, thus providing a great adaptability for various types of construction. When the section 24 is inverted, the distribution of stresses is reversed so that the portions which `formerly carried tension stresses now carry compression stresses, and vice versa.

In the roof 22. shown in FIGURE 4, which is similar to the roof 22 in FIGURE 3 except that it is supported by four columns 72 (only three are seen) which are located at the mid points of the outside edges, the stresses are also all reversed from those in the roof 22. Thus, the ridges 73 of the roof are all in compression. It is preferable to hold the tops of the columns against the thrust of the ridges 73 by tie bars 69 (shown dotted) running under the roof between the tops of opposite columns.

In order to provide for this adaptability of construction, the edges of the section 24 are strengthened by rigid members or ribs of particular shapes, as shown in FIG- URES 18A through 18E described hereinafter, and acting as suitable rain gutters, assembly flanges, wall caps or wall supports, as the case may be, and readily adapted to weather proofing.

The two horizontal edges 45 and 45A are provided with edge stiifening ribs 74, which have portions which project upwardly from the surface 47 and act as rain gutters when the section 24 is assembled in a roof such as the roof units 22 and 22 (-FIGURES 3 and 4). See FIGURE 18C wherein an enlarged cross sectional view of of an edge rib 74 is shown at the edge of a roof surface '75. The rib 74 has a gutter channel '76 and small and large anges 77 and 78 thereon which may project downwardly for use in joining the sections together, and for other purposes, such as to cap the top of a wall '79 shown in phantom lines.

The stilening edge ribs Sti along the inclined edges 46 and 46A (see FIGURES 8 and 18A), have portions 81 which project downwardly from the roof surface 75 and in which suitable bolt holes are prefabricated so that, when used in a roof the various sections can be assembled easily and rapidly from underneath. When the sections are inverted and used in a roof, the portions S1 act as gutters, and the gutters 76 (which have suitable bolt holes) are adapted to be bolted together from underneath. The ribs 80 may preferably have small and large top ilanges 82 and 83, respectively; so that their shape is the same as that of the ribs '74 except that they are inverted when the section 24 is prefabricated. Thus, when the section 24 is turned upside down, for example to form a four-corner supported roof unit 20 (FIGURE 2) the outside inclined edge ribs 80 provide the roof with rain gutters S1 (one half of FIGURE 18A inverted). The

'horizontal ribs 74 form the ridges of the roof. Under the ridges, the gutter portions 76 (see FIGURE 18A) now project downwardly and abut against the corresponding adjacent edges of the other sections of the roof 20. These are suitably drilled and allow the roof to be assembled rapidly from underneath, as by bolts or rivets.

inasmuch as the outside inclined edges of the roof 20 carry compressive stresses, due to the reversal of stresses when the sections are turned upside down, in certain applications it is desirable to use tie bars S4 (please see FIGURE 2), with turnbuckles 85, effectively attached between the tops of the columns 40.

Referring to FIGURE 1, the two pai-rs of end sections 3l and 32, and 37 and 38, provide a compressive thrust at the tops of the columns 42 making it unnecessary to use any tie bars along the edges of the center roof unit 20a parallel with the outside walls. With the enlarged cross-shaped house mentioned above the four columns are all in equilibrium at their tops without any tie bars.

In FIGURE 6 Iis sho-wn a large area roof built up from a number of roof units 22a, each similar to the center supported unit 22. Although many of the advantages of the prefabricated hyperbolic paraboloidical construction disclosed herein have already been seen, the advantages become quite striking in a larger roof such as is shown in FIGURE 6. In this roof each of the units 22a is entirely self-supporting and requires only a single column 86. Thus, there is no requirement for extra supporting structures at the abutting edges of the units. The outside edges of the roof as a whole have no residual forces or loads to be balanced or supported by the side walls. Since there are substantially no bending stresses in the roof units, they are relatively thin and light in weight. There are no rafters or trusses under the roof, and so the columns 86 can be quite light, and the only foundation which is required is a footing under each column. No heavy outside foundation is required, the side Walls may be light in weight, or in fact, for a pavilion such las used over a recreational area, the side walls may be omitted entirely.

-the four Since the units 22a are all individually supported, in some applications it may be desirable to provide expansion joints or other flexible coupling between the units.

A relatively extensive iioor space is provided quite economically, the construction of the whole building may be quite rapidly done and With a relatively small amount of labor. The procedure is to put in the footings, which may be concrete `blocks cast in place, or for light roofs, they may be Prefabricated column supports which are merely driven into the ground. The `columns are erected, and then the roof units 22a are assembled one by one in any order which is desired.

In constructing the units 22a in such a roof, it is preferable that the outside corners of the four sections composing the units be temporarily supported until the four inclined ridges 7l (FIGURE 3) formed by the ribs 80 (FIGURE 18A) are completely fastened together, at which time the roof unit is completely self-supporting around its periphery. In small light-weight units of this type, for example, composed of aluminum sheet and aluminum edge rib members, it is not even necessary to erect four sections at the same time. I have built these units experimentally putting up only two sections on one side and then the two sections on the other side, and the construction was very satisfactory, requiring a minimum of labor and material. However, in general it is preferable to use the balanced procedure of erecting the four sections together before the corners of the unit are left unsupported.

In' order to emphasize the advantages of the ways in which the stresses distribute themselves in the hyperbolic paraboloidical membrane sections ofthe roof shown in FIGURE 6, reference is made to FIGURE 7, showing a vertical cross section taken from corner to corner of the roof. This shows the parabolic arched form of the roof, in which the tops of the columns 86 are acting much like the supporting towers on suspension bridges, with the roof forming parabolic spans S8, therebetween. The tops of the columns are in equilibrium and require no extra bracing.

In FIGURE 9 is shown another form of hyperbolic paraboloidical roof unit 89 having four skylights 90 extending from the peak of the roof down to the centers 92 of the eaves of the roof. It is an advantage of the prefabricated hyperbolic paraboloidical sections such as the one shown in FIGURE 8 that when four of them are assembled they form a unit which is essentially in equilibrium. Thus, in the unit S9, which is supported on four closely spaced central columns 94 forming in eiect one large central column, no stresses are applied to the skylights 90 except their own weight and the weight of any snow which may land thereon. The centers 9T, of the eaves of the roof comprise a single compression member as shown, to transfer the compressive stresses in the outr ide edges, ydescribed above, Without affecting the skylights.

FIGURE l0 shows another large area roof 96 cornposed of umbrella-type units ZZb similar to the unit ZZ in FIGURE 3 and each with a supporting column 98 and composed of inverted-umbrella-type units 23b, similar to the -un'it 23 in FIGURE 5, and each having columns 1001. It should be noted that in the roof 23 in which each of refabricated lsections are inverted the stresses are reversed from those in the roof unit 22. The inclined ribs S0 are in compression and the horizontal edge ribs 74 are in tension, greatest at the mid points 101 of the edges. The large roof 96 includes skylights HB2 running the full width of the roof. Since each of the units 2212 and 23b in the roof 96 is self-supporting around its periphery, the skylights 102 can be merely hung therebetween, -and `do not carry any of the roof stress per se. `These skylights may be vertical, or somewhat inclined,

as shown, which has the advantage of providing a somewhat lgreater oor area for the same size roof units.

The units 23h are of the inverted umbrella-type and all of the water thereon drains down toward the central supporting columns ltl which act as rain drains being tied into a suitable sewer system under the floor of the building. In view of the light weight of the roof units, a relatively large oor space is economically obtained and having a relatively great area of skylighting.

From this description it will be seen that the form of the roof 96 can be modified, for example by alternating rows of units 22h with units 23b so as to obtain skylights between each row.

FEGURE ll is a vertical sectional View taken on a diagonal line ll1l extending from one corner of the roof 96. This section emphasizes the flexibility of const-ruction using prefabricated sections similar to the sections 24 which can be inverted, and again shows that the tops of the columns g3 and Ni) are in equilibrium with each column in effect supporting only its own section of the roof.

FIGURE 12 is a vertical section through the center of a prefabricated housing unit lila of a more inexpensive kind than lthat shown in FIGURE l. The roof is composed of an umbrella-type unit 22e on a column 196 supported by a prefabricated footing or foundation unit IGS, which is adapted to be driven into the ground or buried in the ground. The side walls 1w of such a housing unit are arranged to Ibe entirely supported from the edge of the roof and to hang down into a drainage gutter 112 in the ground.

Such `a prefabricated unit is well adapted to be used by military, engineering, or exploring personnel. The four sections of the roof unit 22C are all identical in form and nest together for easy storage `and transportation, being made of thin gauge aluminum, galvanized or black steel or plywood (the Iblack steel is used where the roof is to be painted) with relatively light edge stiifening ribs. The central column 06 may be made in sections which telescope Within one another and are locked in place by shear pins or bolts, or the various sections of the column lf2-6 may be screwed together.

The side walls lit) may be made of canvas or plastic with lwindows and doors pre-cut therein. The walls may abe vertical or inclined, as shown. This slight inclination serves to give added lateral support to the column, for example, better to resist arctic winds. The column footing NS is formed from several fins of sheet steel, or sheet aluminum and is similar in over-all configuration to the footing M4 shown enlarged and in perspective in FIG- URE 13. The taper of the trapezoidal ns on the footing tu?, with wide part at the top makes it easier to drive into stiff soils where a great supporting effect is obtained near the surface. The four ns of the footing lle have their lgreatest area further down and are more satisfactory in softer soils. The fins 114 are welded at their inner edges to a plurality of rings IIS which have an inner diameter to tit snugly around the base of the column 106. When these units 16S or 1M- are to be driven into the ground, a post hole with a. diameter slightly larger than' the column ille is dug and then the rings 138 of the unit are centered over `the hole, `and it is driven down. Either of the units may also be used merely by digging a hole, burying the unit with its ytop approximately parallel with the ground, and then iilling in the earth around it and then packing the earth down.

In FIGURE 14 is shown a vertical section through a Prefabricated house M9 of a more permanent type than the housing unit 194 and all essentially supported from a single central column lit) resting in a foundation block IZZ so as to be raised above ground level. This type of structure is valuable where there are great numbers `of various pests such as in tropical countries or for ground insulation, as in the Arctic. Because of its prefabricated fonm it can be transported 4to these remote areas. It requires a relatively small amount of bulk material such as cement because of the small compact foundation used. The roof is an umbrella unit 22d, and the oor 124 is spanned between the center column and a cantilevered supporting edge 126 running all the way around the house and supported by a prefabricated inverted-umbrellatype supporting structure 12S having a general over-all configuration like the unit 23 (FIGURE 5), and including four inverted-hyperbolic paraboloidical sections such as shown in FIGURE 8. The inclined bottom surface 131) of this supporting structure is like the top surface of an umbrella-type roof (see FIGURE 3) and is composed of sheet material such as aluminum or steel, etc. and hence it is quite impervious to rodents and pests.

Also, it provides an insula-ting air space between i-tself and the -oor 124, which, coupled with the fact that there can be substantially no direct heat conduction into the ground, makes the unit 119 well adapted for arctic conditions where the ground is deeply frozen.

The stairs may be designed to be raised, where desirable, in the manner of a drawbridge. The side walls 132 maybe hung from the edge of the roof or supported in part or in whole from the edge 126 of the supporting structure 12S. As will be seen from the more detailed description of the edge stitening ribs for use in the pre fabricated hyperbolic paraboloidical sections, those on the lower periphery of the roof unit 22d serve as caps and those on the top of lthe edge of the supporting structure 128 serve as supports for the walls.

Auxiliary supports 134 for the four corners of the house may `be used and be provided with downwardly sloping conical guards or skirts 136 to prevent pests from entering Ithe house. Moreover, the supports 134 offset the strong turning moments of high Winds, which may enable further reduction in the size of the foundation 122.

A modified form of such a center supported housing unit 138 is shown in FIGURE 15, including a center column 129e, a foundation block 122e, an umbrella-type rooting unit 22e, and an umbrella-type hyperbolic paraboloidical supporting structure 140, with a shape similar to the roof 22e.

In order to adapt the unit 138 to various soil conditions, the support 146 may be used primarily under tension to support the side walls 142 which extend down below the level of the iloor 124e. With this arrangement the entire load is carried by the `foundation block 122e. Alternatively, the support 140 may fbe used under compression as an auxiliary support for the column 120e rboth to resist lateral detlections and to absorb vertical loads, in which case small footings 141, shown in phantom, may be used. When the hyperbolic paraboloidical support 14@ is used in this second manner as a brace for the column 120e, the side walls 142 can be supported from the periphery of the roof as where canvas or plastic materials are used, or be supported partly or entirely by the ground `footings 141.

It is to be noted that just as in the case of the unit 119, the supporting structure 140 provides a continuous barrier against the entrance of pests and provides an insulating air chamber. Also, it is an advantage that the unit 13S has two separate insulating air spaces: one between the oor and the surface of the supporting structure 146, and the second between the ground and the structure 140.

In FIGURE 16 is shown an enlarged perspective view of portions of the peak of an umbrella-type of roof, such as the unit 22 shown in FIGURE 3, showing the way in which the prefabricated hyperbolic paraboloidical sections 24'11 are assembled. FIGURES 18A and 18B show enlarged sectional views of the form of the inclined-edge sti'lening ribs Si) which surround the membrane surface 75 of the sections and adapts them for rapid assembly into the various types of roofs discussed above.

The column for the roof is also prefabricated and cornprises a short length of prefabricated round (or square) pipe 144 which in turn is bolted to the top of the longer bottom portion 145 of the column. The top part 144 of the column is of a length approximately equal to the difference in length of column required for a root 22 (FIGURE 3) and a roof 2t) (FIGURE 2) with equal headroom clearance. The top part :144 of the column may ibe made in four longitudinal, arcuate channel pieces 146, each with an oiset 147 to accommodate the top of the column 145 (see FIGURE 17 which may also be made in four longitudinal pieces. These pieces of the column have ilanges and are bolted together. The oiset 147 in the top 144 allows it to telescope over the column 145 and all of the flanges are bolted together in the telescoping portion, as seen in FIGURE 17.

An alternative arrangement is to use four longitudinal, squarely shaped channel pieces, as shown in FIGURE 17A, to form the two parts of the column as squares in cross section. These pieces are teles-coped in the same manner as the circular column shown. The dianges `on the top 144 of the column serve as vanes adapted by suitably arranged bolt holes 150 therein to Ibe secured to generally trapezoidal shaped web plates 152A and B which in turn have their upper inclined edges secured to the edge ribs 8i) to transfer the load from the roof to the column 144, 145, and at the same time to distribute the stresses over an area of the roof whereby they are absorbed by the upper corners of the mem-brane surface '75 of the roof itself, resulting in the elimination of substantially all bending stresses in the edge ribs 80. The web plates `152A and 152B also stabilize the roof against eccentrically applied loads (as caused by persons standing on a corner of the roof) or turning forces developed by the wind. Where several of these roof units are used together as in the roof shown in FIGURE 6, there is a mutual stabilizing eiect, and the web plates are not required to stand such large eccentric loads.

As explained above (see FIGURE 18A), the edge ribs 89 on the inclined edges of the sections 24b have flange and web portions 81 which project below the membrane surface 75 of the roof. These are prefabricated with holes whereby the abutting ribs 80 from two adjacent quadrangle sections are readily bolted together from underneath. Toward the peak of each section, each of the inclined ribs 80 has an olIse-t 156 (see FIG. 16) in a direction away from the abutting rib to provide space 157 (see FIGURE 18B) therebetween for the insertion of the upper inclined edges of the left-hand and righthand web plates 152A and 152B, which are placed back to back. The advantage in flexibility of construction resulting from the use of two such web plates rather than in the use of a single plate twice as thick will become apparent. The web plates 152A and 152B have stillening anges 15S at the lower edge formed by a right angle bend in the metal. The long vertical edges 160iy of the web plates (see also FIGURE 19) each are oiIset in opposite directions enough to accommodate the thickness of one-half of the vanes 148 on both sides of which they are secured as by through bolts or rivets 159. The short vertical edges 162 of the web plates 152A and 152B also are oiset, for these same webs are individually used (see FIGURE 19) in the construction of a fourcorner supported roof, such as the unit 20 shown in FIGURE 2 wherein the prefabricated sections are invetted. The short vertical edges '162 of these webs are also bolted or riveted together (FIGURE 16) through a short rectangular piece of sheet stock (indicated in dotted outline in FIGURE 16) which tits into the offsets and prevents their being bent when the bolts or rivets arc tightened, thus holding the webs back to back, as shown.

In order further to strengthen the peak of the roof, four angle braces 163 are used. having the shape shown in FIGURE 16A, with a pair of spread legs 164 meeting in a corner 165 and a cross Ibrace 1&3 extending diagonally Ibetween the legs. When installed each of the legs 1 1 has an inclination et to the horizontal, corresponding to the inclined edges 46 and 46A of the prefabricated sect-ion (FIGURE 8), so that they will lie along the inside of the web of the ribs Sil as shown in FIGURE 16 and indicated in cross section in FIGURE 18B.

The corners 166 of these angle braces 163 extend beyond the ends of the edge ribs Sil' and run up to the very peak of the roof so as to carry a triangular continuation of the membrane surface 75 up thereto.

It is among the advantages of the ribs shown in FIG- URES 18A and 18B, 18C and 18D, that a channelshaped cap 169 may be slid down over the outside of the two larger iianges, such as iianges S3 shown in FIG- URES 18A and 18B, of the abutting ribs Sti so as to weatherproof the junction between the prefabricated sections. This cap is not shown in FIGURE 16 in order to show more clearly the details of construction. A similar shaped cap can be used over the flanges 78 (FIGURE 18C) and 176 (FIGURE 18D) of the ribs 74 and 17d, respectively. In roofs using the ribs 172, the junctions are covered by long V-shaped channels having a shape generally similar to the combined overlapping portions, generally indicated at 171 in FIGURE 23, described more in detail hereinafter.

In FIGURES 18D and 18E are shown modified forms of the horizontal edge ribs y176 and 172, respectively, which may be used in prefabricated hyperbolic paraboloidical sections corresponding in function to the rib 74 shown in FIGURE 18C. The rib 17) has a curved gutter portion 174 and a pair of depending anges 176 for capping or supporting walls, etc. as in the case of the flanges '77 and 76 (FIGURE 18C). It is understood that in a prefabricated section using the edge rib 170 along the horizontal edges, a similar but inverted rib is used for each of the two inclined edges of the section. The edge rib 172 has a rectangular gutter portion 177, but there are no anges such as -176 in FIGURE 18D, and instead the bottom leg 178 is inclined, correpsonding to the inclination of the surface 179, thus obviating the need for any bend in the surface, such as occurs when the surface 75 (FIGURE 18C) laps over the leg of the rib 74. It is to be noted that the roof sections whose edges are shown in FIGURES 18D and 18E are adapted to be inverted and assemble in the various fashions described above and described in detail hereinafter. The edge rib 172 is adapted for use in buildings without walls which must be capped; and also sections with ribs 172 are adapted for use in the center portions of large area roofs such as shown in FIGURE 6.

Among the advantages of Prefabricated roof sections embodying my invention is the fact that they nest or stack together into a relatively small volume for ease in storage and shipment. This is true of all of the prefabricated sections, having the different shapes of edge stiiiening ribs shown. For example, the edge rib 172 allows the sections to be particularly closely nested together, as shown in FIGURE 26, because of the absence of bottom anges. The horizontal ribs 172 (as shown by the left-hand side of FIGURE 26) lit against the gutter portions 177 of the section below, and the inclined ribs 172 (as shown by the right-hand side) overhang the portions 177 of the sections below.

In FIGURE 19 is shown an enlarged partial perspective view of one of the corners of a roof such as the roof unit shown inFIGURE 2, wherein the sections 24h, corresponding to the section 24 shown in FIGURE 8, are all turned upside down. The webs 152A and 152B are now used individually as shown and their short vertical edges are secured by rivets or bolts 182 to vanes 183 formed on the sides of the column 136 near its top. These vanes may comprise the top portions of the iianges 183 on the edges of the bottom column pieces (see FIG- URE 17). Since the sections are inverted, the ribs Si? are upside down with respect to the position shown in FIGURE 16. The oifsets 156 allow clearance for the top inclined portions of the web plates 152A and 152B which are riveted or bolted thereto. In order further to strengthen the corner, an angle brace 163, identical with those used for the peak of the roof is added as shown and secured by the same bolts or rivets 188 as the web plates 152A and 152B. It should be noted that the hollow interior of the column 186 may act as a rain drain, particularly in an inverted umbrella-type roof such as shown in FIGURE 5, which is composed by four sections and four quadrants (as shown in FIGURES 17 and 19) placed together, without the tie bars 84.

Among the advantages of the quadrant shape of the column 186 and the olsets 156 in the ribs 88 is the fact that where several of the roof units 2G are placed together, there is a proper iit and the quadrant shapes of the columns add together to form a single circular shaped column, which is also the case Where an inverted umbrella-type roof is made, as indicated above.

In FIGURE 20 is shown a partial perspective view of the central portions 719 (FIGURE 3) of the horizontal edges of an umbrella-type of roof unit 22, showing the structural arrangement. The horizontal ribs 74 (see FIGURE 18C) of the two adjacent sections butt together along the seam 190 and are secured together by a length of angle iron 192 (see also FIGURE 20A) which lits between the flanges 77 and 78 and is bolted against the larger one 7S. Additionally, the inner corners of each of the roof sections are reinforced by angle braces 194 having a leg 196 iitting within the inverted gutter portion 81 of the rib Sil, in the same manner as the leg A164iof the angle 163 (FIGURE 18B). And the other leg 198 of the brace 194 is bolted against the same long bottom flange 7 S as the angle iron, with a diagonal brace Ziltl extending between the legs 196 and 198. It is to be noted that the angle iron 192 is staggered beyond the angle brace 194, as indicated by the broken end shown in FIGURE 20A.

In order further to strengthen the rib 74 against the compressive stresses therein, an L-shaped brace 202 is used. The short inclined leg 204 of this brace is bolted between the upright ilanges 82 and 83 of the inclined rib and the long leg 206 lies along the bottom of the gutter portion 76 of the horizontal edge rib 74. The length of the leg 206 of the L-brace is even greater than the length of the angle 192, as shown in FIGURE 20A. Thus, all three of these braces 192, 194 and 202 have legs of staggered length to give progressively greater strength toward the seam 19).

In FIGURE 2l is shown an enlarged pan-.tial perspective view of an outside corner portion of a roof unit 22 (FIGURE 3) such as the corner 66. In order to stiften this corner 66, an angle brace 208 is used, having a pair of legs 216 which are bolted within the gutter portions 76 of the edge rib 74 adjacent to the corner 66, with a diagonal member 212 extending across the corner on top of the roof surface 75, as shown.

An L-shaped angle 214 is used to provide further stiffening for the corner, having a pair of legs 216 which are inserted underneath the rib 74 between the depending iianges 37 (see FIGURE 18C) and bolted between flanges 77 and 78 against the longer flange 78.

In FIGURE 22 is shown a perspective view of a roof constructed from hyperbolic paraboloidal sections 220 having .a quadrangular projection on the horizontal plane with no parallel sides. These sections may be built up from a rectangular layer 222 of sheet material, as shown in FIGURE 23, with a layer of corrugated material 224i `applied to the under surface to somewhat increase the stiffness of the surface of the roof. This stilness may be advantageous where the roof may be called upon to carry non-uniform loads or moving loads, such as occasioned by the necessity for several persons to work thereon in the same general location. In order to till in the extra area to form a completely rectangular horizontal projection for `the roof shown in FIGURE 22 an insertion i3 of four long narrow isosceles triangular shaped spines having a generally box-like cross section is made. These sections are formed by the upright legs `of the angles 228 which terminate the edges of the roof sections together with V-shaped overlapping portions 171. FIGURES 24 and 25 show a generally hexagonal roof 230 built from three prefabricated hyperbolic-paraboloidical sections 232 having a rhombic projection. The roof can be supported on a single central column under the peak or by three columns at points 234 equally spaced around the periphery of the roof, in the latter case using three tie bars from the tops of the columns to a single point directly under the peak.

An example of specific dimensions and materials used in a roof embodying my invention is a roof 22 feet by 22 feet in size using four prefabricated sections in which the two horizontal edges are ll feet long and the two inclined edges rise up to a corner 5 feet above the plane of the eaves of the roof. This provides a height to span ratio (pitch) of 5/22 or somewhat less than 1/4. In general I have found that the pitch should be in the range from l/ 4 to 1/ 6, for the proportionate tangential stresses in the roof increase inversely as the pitch, and for pitches less than 1/6 these stresses tend to become too great. Thus, the angle a shown in FIGURE 8 has a tangent in the range from l/ 2 to 1/ 3. Also, for smaller roofs, such as the 22 foot square one discussed above, the pitch is generally nearer the larger value above, which reduces the stresses and allows thinner sheet material to be used. Whereas, for larger roofs the pitch is nearer the smaller value above in `order to prevent a great diterence in the height of the eaves and of the roof peaks and to save in the total area of the sections by accepting the somewhat greater proportionate tangential stresses resulting from the more shallow pitch.

In general, prefabricated sections having a square projection are the most economical in material, for the stresses are a minimum in proportion to the area covered. Rectangular, rhombic and generally quadrangular sections may be used, but when these deviate greatly from a square, the thickness of the membrane surface must be relatively increased in proportion to the total area covered. Moreover, sections with projections which are square or rhombic have the advantage of being universal for they are reversible and can be used at any place in the roof, but sections whose projections are rectangular or parallelograms are left and right-handed, i.e. they are reversible but should be used in pairs.

In the speciiic 22 foot square roof discussed above, an aluminum sheet approximately .064 inch thick is used, for example 14 or 15 B. and S. gage material, -for the membrane which is stretched and formed into a hyperbolic paraboloidical shape in a single operation. With this prefabrication, a 22 foot square roof can be put in approximately an 1l foot square package, approximately 8 inches thick and weighing 650 pounds. The form of edge rib shown in FIGURE 18E allows a slightly more compact packaging.

The stiiening rib 74 in this embodiment (FIGURE 18C) is aluminum and has a gutter 76 Which extends 2.60 inches above the bottom surface of the web, which extends between the flanges 77 and 78. The overhanging lip on the gutter is 0.75 inch in depth, the gutter is 2.00 inches in width, the flanges 77 and 78 are 2.00 inches apart measured between their outside surfaces. The short -ange 77 is 0.75 inch long, and the other flange 78 is 1.50 inches long, giving an overall height of 2.40 inches, for the edge rib as a whole. The smaller radii near the ilanges and 3/32 inch and the other radii within the gutter are 1716 inch, and all parts of it are 0.10 inch thick. There same respective dimensions apply to rib 80, which is inverted during prefabrication.

The rib 170, if used in the specific embodiment now being described, is the same except that the gutter has 14 a corresponding height of 2.75 inches and an external radius of 1.00 inch.

The rib 17?., if so used, has an overall height of 3.50 inches, the bottom web 17S is 3.75 inches long and rises 1.00 inch at the outside edge. The top of the gutter is 2.50 inches wide with a lip .50 inch long.

The central column has a radius of approximately 5 inches. The top portion 144 is 5 feet long plus an otiset portion of 15 to 20 inches long and the bottom column portion is seven or eight feet long plus a length to reach into the foundation. Each of the quadrants of the columns, Whether the columns are round or square, roughly has a W cross section where the outer legs of the W are not so long as one-half of the central portion.

The relative staggered lengths of the leg 198, one-half of the angle 192, `and the leg 206, are l/2i/3 to provide a uniform tapered stifrening eiect, being `1-2, 24, and 36 inches long, respectively.

At the corner, as shown in FIGURE 21, a staggered eiect is also obtained, `for the diagonal member 212 joins the leg 210 at a point approximately 12` inches from the corner, the leg 210 is 24 inches long, and the legs 216 of the angle are 36 inches long, giving a ratio of 1/ 2/ 3. Also, the end of the leg 210, beyond its junction with the diagonal brace 212 is only about as thick as the remainder of the leg 2110.

The web plates `152A and B, for such a specific embodiment are 22 inches long, 13 inches high at the long vertical edge I and approximately 7.10 inches long at the short vertical edge 162, including in this second measurement the part which projects up alongside the rib 80. They are 0.25 inch thick with a 2 inch ange 15S.

As used herein, a rhombus is intended to include a square From the foregoing, it Will be apparent that the -prefabricated hyperbolic, paraboloidical building sections incorporating the present invention are well-adapted to attain the ends and objects set forth herein, and that the illustrated constructions are subject to a wide variety of modifications so as to best iit the roof unit to the needs of each particular use. It will be seen from the :foregoing also, that various features of the invention may be used at times to advantage without a corresponding use of other features.

I claim:

1. A prefabricated hyperbolic paraboloidical building section having a quadrangular projection comprising a first pair of adjacent substantially horizontal straight edge ribs meeting in a first corner, a second pair of adjacent inclined edge ribs meeting at a second corner diagonally across said building section from `said irst corner, a continuous hyperbolic paraboloidical surface stretching between said ribs, said -iirst pair of edge ribs as seen in vertical cross section having an inclined leg parallel to said surface and secured to said surface, a vertical web projecting up from the outer edge of the inclined leg, and a horizontal leg secured to the top of the vertical web and projecting inwardly in overhanging relationship above the inclined leg, thereby dening a three-sided channel projecting entirely upwardly from said surface, and said second pair of ribs as seen in vertical cross section having an inclined leg parallel to said surface and secured to said surface, a vertical Web projecting down from the outer edge of the inclined leg, and a horizontal leg secured to the bottom of the vertical web and projecting inwardly in spaced relationship beneath the inclined leg, thereby defining a three-sided channel projecting entirely downwardly from said surface, whereby said sections are reversible in use and are readily adapted to `be assembled together in building construction.

2. A prefabricated easily nested hyperbolic paraboloidical root section comprising, a first pair of adjacent substantially horizontal straight edge ribs meeting at right aoco, rea

angles in a iirst corner, a second pair of adjacent inclined edge ribs meeting at a second corner diagonally across said roof section from said `rst corner, a continuous hyperbolic paraboloidical surface stretching between said ribs, said lirst pair of edge ribs having a horizontal web secured to said surface, a vertical web projecting upwardly and downwardly -from the outer edge of said horizontal web, and a horizontal leg spaced above said horizontal web and secured to said vertical web, said horizontal leg projecting inwardly over-hanging said horizontal web, and said second pair of ribs having a horizontal web secured to said surface, a vertical web projecting upwardly and downwardly from the outer edge of said horizontal web, and a horizontal leg spaced beneath said horizontal web and secured to said vertical web, said horizontal leg projecting inwardly beneath said horizontal web, whereby four of said sections are readily adapted to be assembled together either right side up or upside down to form various roof units.

3. A reversible pri-fabricated hyperbolic paraboloidical roof section comprising, a rst pair of adjacent substantially horizontal straight edge ribs meeting a-t right angles in a yfirst corner, a second pair of adjacent inclined edge ribs meeting at a second corner diagonally across said root section `from said iirst corner, a continuous hyperbolic'paraboloidical surface stretching between said ribs, said irst pair of edge ribseach having a iirst web extending inwardly along the edge of the surface and connected to the edge of the surface, a second web extending upwardly from the outer edge of said riirst web, a flange spaced above said :tirst web and projecting inwardly thereover, and a pair or" spaced parallel vertical ilanges projecting downwardly from said first web and extending in -a direction parallel to said webs, and said second pair of ribs each having a first web extending inwardly along the edge of the surface and connected to the edge of the surface, a second web extending vdownwardly from the outer edge of said rst web, a flange spaced below said iirst web and projecting inwardly thereunder, and a pair of spaced parallel vertical flanges projecting upwardly from said iirst web and extending in a direction parallel to said last-said webs, whereby four of said sections are readily adapted to be assembled together either right side up or upside down to -form various roof units.

4. A prefabricated housing unit with flexible walls comprising a single central column, four arms radiating from the top of the column, an umbrella-type roof supported on said arms, said roof comprising four prefabricated sections, each section having a` hyperbolic paraboloidical surface configuration `and having a quadrangular horizontal projection, two of the edges of each of said sections having horizontal stitlening edge ribs with portions projecting upwardly 4from the roof surface forming gutters, two of the edges of each of said sections having inclined stiffening edge ribs with portions projecting downwardly, said inclined stiiening edge ribs having their upper ends oiset from their lower ends, said sections being secured together along their inclined ribs with the offset upper ends of said inclined ribs providing a space therebetween, one of said arms being secured between the inclined ribs and the oiiset upper ends of the inclined ribs, and flexible wall portions hung down vfrom the edges ofthe roof and supported therefrom.

5. A roof unit supported from its four corners comprising four columns standing at the corners of a rec-tangular area, each of said columns having a pair of arms radiating from its top, the upper edges of each of said arms being upwardly inclined in a direction away from the respective column associated therewith, four prefabricated sections each having a membrane type surface of hyperbolic paraboloidical coniiguration with a rectangular projection and with two adjacent horizontal edge stitening ribs with portions extending below the roof and two inclined edge stiliening ribs with portions extending above the roof, the horizontal ribs of each of said sections being placed alongside of thehorizontal edges of adjoining roof sections and secured thereto to form the ridges of the roof, and the pair of inclined ribs of each of said sections being secured near the corner of the roof to the inclined upper edges of the arms `at the top of one of said columns, and four tie bars, each of said bars ettectively extending between the tops of two adjacent columns, whereby the tops of said columns are in equilibrium.

6. A preiabricated housing unit comprising a single central supporting column, four hyperbolic paraboloidical sections with straight edge ribs being secured together along their inclined edges to form an umbrella-type roof having a peak projecting upwardly and being secured to said central column, four more hyperbolic paraboloidical sections being inverted and joined together to form an inverted umbrella-type of supporting structure having a peak projecting downwardly and being secured to said central column with the perimeter of said inverted umbrella-type structure being spaced above the bottom of said central supporting column, the walls 4of said unit extending betiween the edge of said roof and the edge of said supporting structure, and a floor extending over the supporting structure and supported by the edge of the supporting structure.

7. A prefabricated housing unit comprising a foundation structure, a single central supporting column projecting up from said foundation structure, a first plurality of hyperbolic paraboloidical sections each with two straight horizontal yand two strm'ght inclined edge ribs, the inclined ribs or adjacent sections being secured together to form an umbrella-type roof secured to 4the top of said column having a peak projecting upwardly and being over said central column, a second plurality of the same number of hyperbolic paraboloidical sections similar to the sections of the tirst plurality and each being inverted and joined together along their inclined edges to form `an inverted umbrella-type of structure having its inverted peak secured to said column at a point spaced substantially below the upper end of said central column and completely sheltering the bottom of said housing unit from the ground, the walls of said unit extending between the edge of said roof and the edge of said supporting structure, and a floor in said unit supported by the edge of'said supporting structure with the center portion of said tloor supported by said column, said inverted umbrella-type of structure dening an insulation space beneath said door.

S. A prcfabricated housing unit comprising a central foundation structure, a central supporting column projecting up from said foundation structure, a rst plurality of hyperbolic paraboloidical sections each with two straight horizontal edge ribs and two straight inclined edge ribs, the inclined ribs of adjacent sections being secured together to form an umbrella-type roof secured to the top of said column with its peak projecting upwardly and being aligned with said column, a second plurality of the same number of hyperbolic paraboloidical sections joined together in manner similar to the sections oi the iirst plurality and forming an umbrella-type supporting structure having its peak projecting upwardly, said supporting structure being spaced from said roof and being beneath said roof with its peak secured to said column, means connecting the perimeter of said supporting structure to the ground and enclosing the space beneath said supporting structure, thereby sheltering the bottom of said unit, a door in said unit over said supporting structure, and walls around said unit extending between Ithe edge of said roof and the edge of said supporting structure, whereby a pair of air chambers are formed under said floor, one of said air chambers being beneath the floor and above said supporting structure, and the other being beneath said supporting structure.

9. A prefabricated housing unit including a central foundation structure, a central supporting column, a roof surface, and a supporting surface spaced beneath said roof surface with the center of the supporting surface ventically aligned 'with the center of the roof surface, each of said surfaces comprising a plurality of hyperbolic paraboloidical sections, each with two straight edge ribs and two inclined edge ribs, said inclined edge ribs of the adjacent sections of the roof surface being secured together and forming a roof surface with a central peak which is above the perimeter of the -roof surface, said central peak of the roof surface being supported by said column, said inclined edge ribs of the adjacent sections of the supporting surface being secured together and forming a supporting surface with a central peak vertically aligned with the central peak of the roof surface, said central peak of the supporting surface being secured to said column, and walls extending between the peripheries of said two surfaces.

lO. An invertible prefabricated hyperbolic paraboloidical building section comprising, first and second straight edge ribs meeting in `a first corner `and lying in a plane, said ribs each having a vertical web portion at the edge of the section and a top portion with an overhanging fiange turned inward above the edge of the roof surface with a lip on the flange turned downward toward the roof surface, third and fourth straight edge ribs meeting in a second corner diagonally across said section from said first corner, said third and fourth ribs lying in a second plane forming an angle with said lfirst plane, said third and fourth ribs each having a downwardly extending vertical web portion at the edge of the section with a ange extending inward beneath the edge of the roof surface with a lip on the ange turned upward toward the roof surface, said third rib being connected to said second rib and said fourth rib being connected to said first rib, and a continuous hyperbolic paraboloidical surface extending between said edge ribs.

11. A pavilion-type roof unit supported from points equally spaced around its periphery comprising a plurality of columns each having approximately a W-cross sectional form with the outer legs of the W-Shape acting as ver-tical flanges, said columns Standing at the corners of a polygonal area with equal sides, the flanges of each of said columns being parallel with lthe sides of said Iarea adjacent said columns, respectively, each of said columns having a pair of web plates secured to its flanges near its top, and a plurality of prefabricated sections of the same number as said columns and each having a membranetype surface of hyperbolic paraboloidical configuration, each with a quadrangular projection and with two adjacent horizontal edge stiffening ribs and two inclined edge stiffening ribs, the horizontal ribs of each of said sections being placed alongside of the horizontal edges of adjoining roof sections and secured thereto, and the inclined ribs of each of said sections being secured near the corner of the roof to the web plates at the top of a respective one of said columns.

12. A prefabricated centrally-supported roof unit cornprising a central column composed in cross section of four quarters of roughly W-shaped cross sections, with their outer legs lacting as connecting flanges to form a hollow column, four web plates secured to said flanges near the top of the column and radi-ating at right angles ,from said column, and four prefabricated sections each having a membrane-type surface of a hyperbolic paraboloidical configuration with a substantially rectangular projection and with four stifliening edge ribs secured to the four edges thereof, two of said four edge ribs in each section being horizontal and meeting 'at a corner, and two of said four edge ribs in each section being inclined and meeting at another corner diagonally across the surface of the section, the adjacent inclined edges of said sections being secured together to form four inclined ridges one of said ridges being secured to each of said arms.

13. A Prefabricated centrally-supported roof unit comprising a central column composed in cross section of four quarters of roughly W-shaped cross section, with their outer legs acting -as connecting flanges to form a hollow column, four web plates secured .to said flanges near the top of the column and radiating at right angles from said column, four prefabricated sections each having a membrane-type surface of a hyperbolic paraboloidical configuration with a substantially rectangular projection and with four stiffening edge ribs secured to the four edges thereof, two of said four edge ribs in each section ybeing horizontal and meeting Iat a corner, and two of said four edge ribs in each section -being inclined and meeting at another corner diagonally across the surface of the section, said inclined edge ribs including vertical flange extending parallel to the edge of said section, the 'adjacent inclined edges of said sections being secured together to form four inclined ridges, one of said ridges being secured to each of said webs, and four long mernbers of U-shaped cross section, each having its depending edges overlapping the anges on adjacent inclined ribs of adjacent sections to .weatherproof the junctions between sections.

14. A prefabricated hyperbolic paraboloidical roof unit supported from the top of a central column structure comprising a plurality of prefabricated hypenbolic paraboloidical roof sections, each section having a rhombic projection on the horizontal plane `and including a first pair of adjacent substantially horizontal straight edge ribs meeting in a first corner, a second pair of adjacent inclined edge ribs meeting ata second corner diagonally across said roof section from said first corner, a continuous hyperbolic paraboloidioal surface stretching between said ribs, the inclined ribs of said sections being parallel to and spaced from the adjacent inclined ribs of adjacent sections, at least one skylight hung between an adjacent pair of inclined ribs, -anda compression resisting structure extending between `adjacent pairs of inclined ribs between which any skylight is hung, said compression resisting structure being Ilocated near the perimeter of said roof.

15. A large area roof comprising a first row of umbrella-type prefabricated hyperbolic paraboloidical roof units, each being supported from a single central column, each of said units comprising four identical prefabricated hyperbolic paraboloidical sections, each section having ,a rectangular projection on the horizontal plane, a first pair of adjacent substantially horizontal straight edge ribs meeting at right angles in a first corner, a second pair of adjacent inclined edge ribs meeting at a second corne-r diagonally across said roof section from said first corner, and a continuous hyperbolic paraboloidical membrane surface stretching between said ribs, the plurality `of sections within each unit having their inclined ribs secured to the adjacent inclined ribs of adjacent sections and sloping downwardly from the top of the central column, whereby the periphery of each unit in said first row is a horizontal rectangle, and the adjacent ends tof the periphery of each unit `are secured together to form said first row, -a second row of inverted umbrellatype prefabricated hyperbolic paraboloidical roof units, each being supported from a single central column, each of said units in the second row being identical with the units in the second row except that they are all inver-ted so that the adjacent inclined ribs slope upwardly from the top of the central column, said first and second rows being spaced apart, and ya rectangular skylight extending therebetween.

16. A prefabricated centrally-supported roof unit cornprising a central column having four arms secured to the top thereof and radiating outwardly from the column, four prefabricated sections, each having a rectangular projection on the horizontal plane and a surface with a hyperbolic paraboloidical configuration and with four stiffening edge ribs secured to the four edges thereof, two of said four edge ribs in each section being horizontal and meeting at a corner, and two of said four edge ribs in each section being inclined and meeting at another corner diagonally across the lsurface of the section and having' flanges projecting upwardly from said surface and adjacent the inclined edges of said sections, the adjacent edges of said sections beingV secured together to form four inclined ridges, one of said ridges being secured to each of said arms, and four angle braces, each having a pair of diverging legs, said pair of legs meeting at an apex and a diagonal member therebetween, each of said angle braces having its apex positioned above the top of said central column with its diverging legs being adjacent the inside surfaces of the flanges of a respective section and being secured to said flanges.

17. A Prefabricated centrally-supported roof unit comprising a central column having four arms secured to the top thereof and radiating outwardly from the column, said arms having stiffening means extending along their lower edges and having upper edges sloping downwardly from the central column, four prefabricated sections each having a rectangular projection n the horizontal plane and a surface with a hyperbolic paraboloidical configuration and with four stiffening edge ribs secured to the four edges thereof, two of said four edge ribs in each section being horizontal and meeting at a corner, and the other two of said four edge ribs in each section being inclined and meeting at another corner diagonally across the surface of the section from said first corner and having flanges projecting downwardly from said surface and adjacent the inclined edges of said sections, said downwardly projecting flanges of adjacent sections being secured together to form a roof unit having a central peak and a rectangular perimeter, the upper edges of said four anns being secured to said anges, whereby said roof unit is supported by said central column.

References Cited in the file of this patent UNITED STATES PATENTS 304,785 Butz Sept. 9, 1884 20 Thomas Nov. 13, 1888 Peterson Feb. 2, 1915 Benner May 14, 1918 Sexauer Dec. 30, 1919 Lamb Apr. 25, 1922 Doorn Feb. 1, 1927 Pfenning June 17, 1930 Olson Feb. 23, 1932 Bayley Aug. 29, 1933 Mopin July 14, 1936 Creighton Aug. 4, 1936 Guyon Sept. 21, 1937 Rubel Apr. 9, 1940 Gabel Feb. 11, 1941 Black Aug. 30, 1949 Clerk Mar. 24, 1953 Anthony June 9, 1953 Ager Iuly Z1, 1953 Iddings Aug. 1l, 1953 Shaw Apr. 5, 1955 FOREIGN PATENTS France of 1937 Great Britain May 17, 1939 Great Britain of 1946 Great Britain Oct. 19, 1949 Great Britain Sept. 3, 1952 Denmark of 1939 Italy July 12, 1949 italy July 26, 1949 Italy of 1950 OTHER REFERENCES 

1. A PREFABRICATED HYPERBOLIC PARABOLOIDICAL BUILDING SECTION HAVING A QUADRANGULAR PROJECTION COMPRISING A FIRST PAIR OF ADJACENT SUBSTANTIALLY HORIZONTAL STRAIGHT EDGE RIBS MEETING IN A FIRST CORNER, A SECOND PAIR OF ADJACENT INCLINED EDGE RIBS MEETING AT A SECOND CORNER DIAGONALLY ACROSS SAID BUILDING SECTION FROM SAID FIRST CORNER, A CONTINUOUS HYPERBOLIC PARABOLOIDICAL SURFACE STRETCHING BETWEEN SAID RIBS, SAID FIRST PAIR OF EDGE RIBS AS SEEN IN VERTICAL CROSS SECTION HAVING AN INCLINED LEG PARALLEL TO SAID SURFACE AND SECURED TO SAID SURFACE, A VERTICAL WEB PROJECTING UP FROM THE OUTER EDGE OF THE INCLINED LEG, AND A HORIZONTAL LEG SECURED TO THE TOP OF TH VERTICAL WEB AND PROJECTING INWARDLY IN OVERHANGING RELATIONSHIP ABOVE THE INCLINED LEG, THEREBY DEFINING A THREE-SIDED CHANNEL PROJECTING ENTIRELY UPWARDLY FROM SAID SURFACE, AND SAID SECOND PAIR OF RIBS AS SEEN IN VERTICAL CROSS SECTION HAVING AN INCLINED LEG PARALLEL TO SAID SURFACE AND SECURED TO SAID SURFACE, A VERTICAL WEB PROJECTING DOWN FROM THE OUTER EDGE OF THE INCLINED LEG AND A HORIZONTAL LEG IS SECURED TO THE BOTTOM OF THE VERTICAL WEB AND PROJECTING INWARDLY IN SPACED RELATIONSHIP BENEATH THE INCLINED LEG, THEREBY DEFINING A THREE-SIDED CHANNEL PROJECTING ENTIRELY DOWNWARDLY FROM SAID SURFACE, WHEREBY SAID SECTIONS ARE REVERSIBLE IN USE AND ARE READILY ADAPTED TO BE ASSEMBLED TOGETHER IN BUILDING CONSTRUCTION. 